Revert "DenseSet: Appease msc18 to define derived constructors explicitly."

This reverts commit r284570. MSVC 18 / 2013 is not supported anymore.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284661 91177308-0d34-0410-b5e6-96231b3b80d8

Author: rnk

include/llvm/ADT/DenseSet.h

@@ -210,13 +210,7 @@ class DenseSet : public detail::DenseSetImpl<
                            ValueInfoT>;
 
 public:
-#if defined(_MSC_VER) && _MSC_VER < 1900
-  explicit DenseSet(unsigned InitialReserve = 0)
-      : DenseSetImpl(InitialReserve) {}
-  DenseSet(std::initializer_list<ValueT> Elems) : DenseSetImpl(Elems) {}
-#else
   using BaseT::BaseT;
-#endif
 };
 
 /// Implements a dense probed hash-table based set with some number of buckets
@@ -234,13 +228,7 @@ class SmallDenseSet
       ValueInfoT>;
 
 public:
-#if defined(_MSC_VER) && _MSC_VER < 1900
-  explicit SmallDenseSet(unsigned InitialReserve = 0)
-      : DenseSetImpl(InitialReserve) {}
-  SmallDenseSet(std::initializer_list<ValueT> Elems) : DenseSetImpl(Elems) {}
-#else
   using BaseT::BaseT;
-#endif
 };
 
 } // end namespace llvm